Ammonium Chloride → Ethyl 3-(4-aminophenyl)isoxazole-5-carboxylate

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To a solution of the compound of step 1 (1.0 g; 3.8 mmol) and NH4Cl (0.61 g; 11.4 mmol) in EtOH (30 ml), THF (20 ml) and water (5.0 ml), was added iron powder (0.5 g, 8.9 mmol) under vigorous stirring. The resulting reaction mixture was heated at 80° C. under stirring for 3 hours. The reaction mixture was cooled to 25° C. and filtered through celite and washed with EtOH. The filtrate was concentrated and basified with NaHCO3. The oil separated was extracted with dichloromethane (3×20 ml). The dichloromethane layer was washed with water (2×10 ml) and dried over anhydrous Na2SO4. The solvent was evaporated, and the residue was purified by flash chromatography with EtOAc: light petroleum (1:1) to give the title compound of step 2 (0.67 g; 75%). Mass (ES−), 231 (M−1); 1H NMR (DMSO-d6) δ: 1.31 (t, 3H), 4.36 (q, 2H), 5.64 (s, 2H), 6.61 (d, 2H), 7.60 (d, 2H), 7.66 (s, 1H).

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